In prior art train control systems, control signals are sent unidirectionally via the electrical current on the track. Typically, a model electric train runs on a track consisting of at least two electrically isolated rails, and AC or DC electrical power is supplied to the train from a transformer using the rails as electrical connections. In the absence of a handheld controller, the train's speed and other features are controlled by increasing or decreasing the transformer voltage. A limited number of additional train functions can be controlled by the transformer or control unit. For example, some prior art designs include buttons or switches that sound a horn or bell on the train when activated. As disclosed in U.S. Pat. No. 6,281,606 by Westlake, a throttle can be used for varying the voltage, speed and direction of the model train. Model train layout accessories can also be operated by transformers, but, in many cases, a separate transformer is set up for each individual accessory, and often, several transformers are required to operate a multitude of train layout items.
In more recent years, as technology has become more accessible and more complex, model train manufacturers have moved to control system designs which utilize a remote control to allow more flexibility, more functions and implementation of new features not previously available. If a handheld controller is present, the transformer power is turned on continuously, normally at the highest setting, and each train on the track is controlled by addressing the specific ID number stored in the individual trains, and the handheld controller regulates the voltage from the transformer sent to the model train or model train accessory. One remote controller can be capable of controlling several trains or accessories on the same layout. In addition, multiple handhelds can be used to control the same train as long as each controller inputs the specific D number as assigned to that train.
Some existing systems send digital signals to the train using a two step transmission scheme, wherein the signal is sent from the handheld controller to a base unit or track interface unit. The base unit then places the signal on the track. In some cases, the signal is directly decoupled from the track. In other cases, the signal is radiated from the track and received by an antenna in the train. There is an conventional system common in DC powered layouts. It has a radio or wired handheld controller that sends signals to a digital command control device that superimposes a digital signal over the DC track power. The Digital Command Control (DCC) system, a standard maintained by the National Model Railroad Association, is used to in DC powered train control systems. The DCC system requires that all power to the track be routed through a DCC device that places the signal on the track. A similar conventional system operates on AC track power. This system requires that all power to the track be routed through a specific device that places the signal on the track, adding cost and complexity of installation. This system also requires impedance matching between the various track sections, which further complicates the installation by requiring direct wire connections between the track and the special device at regular intervals.
Another two-step transmission scheme, as seen in U.S. Pat. No. 6,457,681 by Wolf et al., includes a remote control, a track interface unit or an accessory interface unit, a track layout system and receiver in the model train. Commands are entered into the remote control by the user. The track interface unit receives and processes these commands from the remote control into signals that are sent over wires to the track rails. The signals are passed along the track rails and picked up by the model train receiver which then executes the commands related to such functions as speed control, operation of lights, operation of sound and train uncoupling, among others. To operate an accessory, this design has the option of sending signals from the remote control to an accessory interface unit connected to an toy train layout accessory. In addition, the Wolf et al. invention has the ability to connect a computer to the track interface unit to produce sounds and other operational functions. This system requires that all power to the track be routed through an additional, specific device that places the signal on the track, adding cost and complexity of installation.
There are some systems on the market using a 27 MHz or IR signal. These are unacceptable on higher quality trains because the signal is lost in tunnels and complex layouts. In one prior design, a two-step transmission scheme is utilized wherein the handheld controller transmits commands at 27.255 MHz to a base which converts the commands to a 455 kHz transmission using the track as the transmitting antenna. An antenna in each train then receives the commands. The reason for this method is that the 27.255 MHz signal is easily blocked by metal bridges, mountains and other structures common on many layouts, and this problem is avoided if the data goes through the track rails.
Another prior art design, U.S. Pat. No. 4,334,221 by Rosenhagen et al, describes a unidirectional system for controlling multiple model vehicles, in this case the vehicles are cars with multiple remote controllers. The Rosenhagen et al. invention uses the same simple random access, receiver error recognition, and command ignoring collision scheme exactly the same way as the 27.255 MHz system mentioned above. The disadvantage to this random access system is that the base receiver detects a collision if the information received has errors, and the transmission is then ignored. Since the system is unidirectional, there is no feedback to the transmitter, and the user may not realize that the command was ignored and should be tried again.
Some prior inventions use a direct radio link, but only in one direction, and at a lower transmission frequency.
Some prior art, for example U.S. Pat. No. 6,494,410 by Lenz and U.S. Pat. No. 6,539,292 by Ames, Jr., includes a bidirectional communication between the model train and the control device, but the communication is not a direct radio link. These systems still require use of a base control unit or track interface unit and that signals are sent over the track. In both cases, the returned data is limited, often just acknowledging the transmission, and does not present further command options to the toy train operator.
Regarding speed control, as previously described, in early systems, the toy train's speed was increased or decreased by manually operating a throttle or knob on the transformer or power supply which increased or decreased the track voltage. Subsequently, speed control was implemented into the remote control system designs, for example, U.S. Pat. No. 5,251,856 by Young et al. and U.S. Pat. No. 6,619,594 by Wolf et al.
In some conventional systems, the handheld controller will display the desired speed inputted by the train operator, but not the actual train speed. If a second handheld controller is then used to adjust the desired speed of the same train, the first handheld will not register the change. Since it is common for two or more handheld controllers operated by two or more people present during a train's operation, this feature of prior designs causes repeated problems in train operation. As an example, if Handheld One was used to set the desired train speed to 40 scale mph and later, Handheld Two was used to change the speed to 5 scale mph, the display on Handheld One would still register 40 scale mph. Then, if the throttle on Handheld One was used to increase the desired speed, the next increment upward would make the train's actual speed to go immediately to from 5 to 41 scale mph, causing an increase in speed that is too rapid and unrealistic. Rapid increases in train speed such as this can easily cause train collisions or derailment.
Conventional systems rely on the radio receiver and its associated processor to control the motor driver, even when a customer does not have a remote controller.
Early versions of smoke units commonly used in the electric train industry operate by powering the fan motor continuously, thereby making a constant stream of smoke. These designs are considered undesirable and very limiting functionally by manufacturers or train operators who want a train to operate as realistically as possible. Therefore, it is desirable to create more realistic puffs of smoke instead of a steady stream of smoke.
U.S. Pat. No. 6,280,278 by Wells discloses a smoke unit that includes two features that are common to most model train smoke unit designs today: a reservoir to hold the smoke fluid or oil and a heating element to raise the temperature of the fluid or oil to create smoke. Wells implements a pump transmitting smoke fluid or oil to the smoke unit; and in this application, the control of the amount of smoke fluid present in the smoke unit determines smoke output conditions. While this design does aid in a system that produces intermittent smoke, manufacturers prefer designs that include greater control of the smoke output to create a puffing effect.
Other prior art, as seen in U.S. Pat. No. 6,485,347 by Grubba et al., employs a motor driven fan to maintain a flow of air through the smoke unit housing and includes a mechanical means of interrupting or temporarily blocking the airflow from the fan. The blocking means opens and closes at a rate synchronized with the train's speed, and the repetitious interruption in airflow results in puff-like smoke output production. Another puff-producing design, as depicted in U.S. Pat. No. 6,457,681 by Wolf et al., controls the airflow by either applying an electronic brake or reversing the voltage to quickly stop the fan motor and thereby produce abrupt bursts of puffs of smoke.
In U.S. Patent Application Publication No. 2003/0064657 by Pierson, a method is disclosed to vary a model train's smoke output in response to a signal indicating changes in the train's load. A microprocessor controller monitors and receives input of the train's load defined as either the voltage across the model train engine or the speed of the train. The input data is processed through a stored control program, and subsequently, to make adjustments to the changes in load, the controller controls the rotation of the smoke unit fan at a predetermined rate, which, in turn, controls the smoke unit airflow.
U.S. Patent Application Publication No. 2003/0155470 by Young et al. utilizes position indicators along a track to attempt to automatically derive layout geometry and result in automated route selection and automated switch selection.